Answer:
Just head and foot yet never tires of dancing.
I drive men mad for love of me. Easily beaten, never free.
You throw away the outside, eat the inside, then throw away the inside. What is it?
I am a precious little thing, dancing and eating all the time. Watch me from a distance, so you can feel my warm and gentle love. But don't come to close or my next meal you could be!
Glittering points that downward thrust. Sparkling spears that never rust.
You use it between your head and your toes, the more it works the thinner it grows.